Underdrain

ABSTRACT

A vertically elongated body is provided at a relatively high level thereon with large openings which communicate with the upper end of central passage extending downwardly through the body to effect a high flow rate during service. Small openings at a level below the large openings communicate with an annular chamber in the lower portion of the body to effect a low flow rate during regeneration. The upper portion of the body in which the large and small openings are formed is surrounded by a tubular screen.

United States Patent dc Boerr 5] Mar. M, i972 [541 UNDERDRAIN 2,085,8247/1937 Mullett ..285/l33 R x [72] Derek Peter de Boem Toronto, 5Ontario, Canada 2,325,464 7/1943 Bannister ..285/l33 R x Assignee: CraneCanada Limited, Montreal, Quebec.

C zmada Nov. 25, 1970 92,664

Filed:

Appl. No.:

Foreign Application Priority Data Oct. 26, 1970 Canada ..096582 US. Cl...ll37/550, 210/293, 285/133 R lint. Cl. i ..lE03f 3/118, B0ld 23/18Field of Search ..210/292, 293, 279; 285/133,

References Cited UNITED STATES PATENTS 1/1899 Agge et al ..2l0/293Primary ExaminerHenry T. Klinksiek Attorney-Fetherstonhaugh and Co.

[5 7] ABSTRACT 8 Claims, 3 Drawing Figures H/GH FLOW RATE LOW FLOW RATEI 19 Ale PATENTEDMARMIBYE 3,648,731

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g Q s 25 1 I 5 1 5: 1! 35 5..

2 LOW FLOW RATE 21 1,? 21 12 11 I 24 Avm 3 L I .1 f

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INVENTOR Derek Peter deBOERR PATENT AGENTS PATENTEUHAR 14 I972 3, 648731 SHEET 2 BF 2 IN VEN TOR Derek Peter deBOERR PATENT AGENTSUNDIERIDRAIN This invention relates to new and useful improvements inunderdrains for ion exchangers utilizing a bed of solid particles tofilter, soften or otherwise treat a liquid. In such apparatus thetreated liquid is discharged from the ion exchange bed through ascreened underdrain, and ion exchangers which facilitate a high flowrate of liquid when the. apparatus is in service. However, with thisaccomplished, a difficulty has arisen in obtaining .a good flowdistribution when using a low flow rate of liquid during regeneration.

The principal object of the invention is to provide an improvedunderdrain which facilitates a high flow rate during service as well asa low flow rate during regeneration, thus affording good flowdistribution over this wide range of flow rates.

Briefly, the underdrain of the invention utilizes differently sizeddrain openings at different levels in communication with differentoutlets, so that an appropriate pressure drop is available for both highand low flow rates to ensure good flow distribution.

The underdrain of the invention is very simple in construccalmanufacture.

With the foregoing more important object and features in view and suchother objects and features which may become apparent as thisspecification proceeds, the invention will be understood fromthefollowing description taken in conjunction with the accompanyingdrawings, wherein like characters of reference are used to designatelike parts, and wherein:

FIG. 1 is a vertical sectional view showing the underdrain of theinvention;

FIG'. 2 is a cross-sectional view, taken substantially in the plane ofthe line 2-2 in FIG. 1; and

FIG. 3 is a cross-sectional view, taken substantially in the plane ofthe line 3-3 in FIG. 1.

Referring now to the accompanying drawings in detail, the improvedunderdrain of the invention is designated generally by the referencenumeral and is intended .to be installed in anaperture 11 in a bottom 12of an ion exchange bed.

The underdrain 10 comprises a vertically elongated cylindrical body 131,which may be formed from suitable plastic material, the body 13 beingprovided with a central longitu dinal passage 14which has a closed upperend and an open lower outlet end 14a. The upper end portion of the body13 is formed with a plurality of relatively large high flow rate drainopenings 15 which communicate with the upper end portion of the passage14. These openings are spaced circumferentially of the body and theiraxes may be slanted downwardly into the passage 14, as shown in FIG. 1,so that the liquid flow through these openings blends smoothly uponentering into the passage.

The lower end portion of the body 13 is recessed to form an annularchamber 16 which surrounds the passage 14 but is isolated therefrom.Conceivably, the body 13 may be moulded with thechamber 16 therein, butas a more practical manufacturingexpedient a tubular base member 17 ofplastic material may surround the recessed lower end portion of the bodyand coact therewith indefining the annular chamber 16. The base member17 has its upper and lower ends suitably secured to the body 13, as by asolvent weld, for example, and an outlet port 18 is provided .at oneside of the base member in commu' nication with the chamber 16. Also, anannular flange 19 may be providedintegrally on or secured to theexterior of the base member 17, the flange 19 being apertured as at 20in FIG. 3 for reception of bolts or screws (not shown) whereby theentire underdrain 111 may be secured to the bottom 12 of the ionexchange bed.

The body 13 is also provided with a plurality of relatively small lowflow rate drain openings 21 which communicate with the annular chamber16, as will be apparent from FIG. 1. These openings are formed in whatmay be referred to as the intermediate portion of the body 13, somewhatabove the ion exchange bed bottom 12, but definitely below the level ofthe relatively large high flow rate drain openings 15 which are locatedin the upper region of the body 13.

The portions of the body 13 in which the drain openings 15 and 21 areformed is surrounded by a tubular screen 22 which has its upper andlower ends suitably secured to the lands23, 241 on the body, it beingnoted that between these lands the body is diametrically reduced so thatthe screen 22 is spaced radially outwardly therefrom. An annular dividerflange 25is formed integrally on the diametrically reduced portion ofthe body 13 at a level between the high flow rate openings 15 and thelow flow rateopenings 21. The flange 25 approximately divides the highflow and low flow rates through the respective drain openings, and inaddition it supportably engages the .inside of the tubular screen 22.The longitudinal span of the screen between the flange 25 and the land23 is considerably greater than that between the flange 25 and the land24, so it is desirable to provide additional means for supporting thescreen against inward collapsing by external pressure of the ionexchange bed material in the region of that greater longitudinal span ofthe screen. Thus, the upper portion of the body 13 between the flange 25and the land 23 isprovided with a set of circumferentially spaced,longitudinally extending ribs 26 which are formed integrally with thebodyand supportably engage the inside of the screen, as is best shown:in FIG. 2. The aforementioned drain openings 15 are spaced so that theyre located between the ribs 26, as shown.

In operation, the underdrain unit 111 is installed in the aperture 11 sothat it projects through the ion exchange bed bottom 12 into the ionexchange material, substantially as shown in FIG. 1. When the apparatusisin service, the liquid to be filtered, softened or otherwise treatedby the ion exchange passes through the ion exchange bed, through thescreen 22 and through the large, high flow rate openings .15 into thepassage 14, being then discharged through the lower outlet end 14a ofthat passage. However, during regeneration, the

liquid flows at a relatively low flow rate through the small openings 21into the chamber 16, from which it is discharged through the port 18.Thus, the underdrainis effectively capable of handling both high and lowflow rates as requiredbyservice and regenerating conditions,respectively, by utilizing the relatively large and small drain openings15, 21, respectively, at respectively higher and lower levels in the ionexchange bed, and discharging through the separate outlets 14a and 18,respectively. In this manner the required. pressure drop over theunderdrain is provided for both the high and the low flow rates in orderto assure good flow distribution.

While in the foregoing there has been described and shown the preferredembodiment of the invention, various modifications and equivalents maybecome apparent to those skilled in the art to which the inventionrelates. Accordingly, it is not desired to limit the invention to thisdisclosure, and various modifications and equivalents may be resorted towithin the spirit and scope of the appended claims.

The embodiments .of the invention in which an exclusive property orprivilege is claimed are defined'as follows.

1. An underdrain foran ion exchanger having a highflow rate duringservice and a low flow rate during regeneration, said underdraincomprising a vertically elongated body adapted to be installed at thebottom of an ionexchange bed, said body having two separate outlets andbeing provided at two distinct levels with two sets of differently sizedopenings communicating with the respective outlets, one set of saidopenings beingrelativelylarge high flow rate openings located at arelatively high level, and the other-set being relatively small low flowrate openings located at a level substantially below the large openings.

2. An underdrain for an ion exchanger having a high flow rateduringserviceand a low flow rate during regeneration, said underdraincomprising a vertically elongated body provided with a centrallongitudinal passage having a closed upper end and .an open lower end,the lower end portion of said body being shaped to form an annularchamber which surrounds said passage but is isolated therefrom, saidchamber having an exteriorly communicating port, the upper portion ofsaid body being provided with a set of relatively large high flow rateopenings communicating with the upper end portion of said passage, saidbody also being provided with a set of relatively small low flow rateopenings communicating with said annular chamber, said low flow rateopenings being disposed at a level on said body substantially below saidhigh flow rate openings.

3. The device as defined in claim 2 together with a tubular screensecured to and surrounding the upper portion of said body in which saidhigh flow rate and low flow rate openings are provided.

4. The device as defined in claim 3 together with a set ofcircumferentially spaced vertical ribs provided on the upper portion ofsaid body and supportably engaging the inside of said tubular screen.

5. The device as defined in claim 3 together with an annular dividerflange provided on he upper portion of said body at a level between saidhigh flow rate and low flow rate openings, said divider flange engagingthe inside of said tubular screen.

6. The device as defined in claim 2 together with a tubular base membersecured to and surrounding the lower end portion of said body, thelatter being formed with an annular recess which coacts with saidtubular base member to define said annular chamber.

7. The device as defined in claim 6 which is further characterized inthat said port of said chamber is provided in said tubular base member.

8. The device as defined in claim 6 together with an annular mountingflange provided exteriorly on said tubular base member.

1. An underdrain for an ion exchanger having a high flow rate duringservice and a low flow rate during regeneration, said underdraincomprising a vertically elongated body adapted to be installed at thebottom of an ion exchange bed, said body having two separate outlets andbeing provided at two distinct levels with two sets of differently sizedopenings communicating with the respective outlets, one set of saidopenings being relatively large high flow rate openings located at arelatively high level, and the other set being relatively small low flowrate openings located at a level substantially below the large openings.2. An underdrain for an ion exchanger having a high flow rate duringservice and a low flow rate during regeneration, said underdraincomprising a vertically elongated body provided with a centrallongitudinal passage having a closed upper end and an open lower end,the lower end portion of said body being shaped to form an annularchamber which surrounds said passage but is isolated therefrom, saidchamber having an exteriorly communicating port, the upper portion ofsaid body being provided with a set of relatively large high flow rateopenings communicating with the upper end portion of said passage, saidbody also being provided with a set of relatively small low flow rateopenings communicating with said annular chamber, said low flow rateopenings being disposed at a level on said body substantially below saidhigh flow rate openings.
 3. The device as defined in claim 2 togetherwith a tubular screen secured to and surrounding the upper portion ofsaid body in which said high flow rate and low flow rate openings areprovided.
 4. The device as defined in claim 3 together with a set ofcircumferentially spaced vertical ribs provided on the upper portion ofsaid body and supportably engaging the inside of said tubular screen. 5.The device as defined in claim 3 together with an annular divider flangeprovided on the upper portion of said body at a level between said highflow rate and low flow rate openings, said divider flange engaging theinside of said tubular screen.
 6. The device as defined in claim 2together with a tubular base member secured to and surrounding the lowerend portion of said body, the latter being formed with an annular recesswhich coacts with said tubular base member to define said annularchamber.
 7. The device as defined in claim 6 which is furthercharacterized in that said port of said chamber is provided in saidtubular base member.
 8. The device as defined in claim 6 together withan annular mounting flange provided exteriorly on said tubular basemember.